An angle detecting device is used, for example, as a rotation angle sensor which detects an operation angle of a vehicle brake pedal or a shift lever for a transmission of a vehicle. Conventional angle detecting devices are disclosed in Patent Documents 1 and 2. These conventional angle detecting devices detect a rotation angle based on the change of the magnetic field. The angle detecting device of the above conventional type includes a magnet magnetized so that the magnetic performance is exerted alternately in a circumferential direction on a rotation member which is the subject of the angle detection. Further, the conventional angle detecting device detects a first magnetic field component in a radial direction and a second magnetic field component in a direction perpendicular thereto relative to the rotation member and calculates the angle of the rotation member based on the detected first and the second magnetic field components which change in response to the rotation of the rotation member.